CR-FREE COATING MATERIAL FOR METAL COATED STEEL SHEET REPRESENTING EXCELLENT ADHESION TO PAINTS AND A PROCESS FOR PRODUCING CR-FREE COATED STEEL SHEET USING THE COATING MATERIAL

摘要

Provided is a chrome-free composition useful for the surface treatment of a steel sheet, which imparts excellent anti-corrosive property, processability, workability, powder coating property and lubrication property to a steel sheet coated with the same. The chrome-free composition is used for the post-treatment of a coated steel sheet, and comprises: 60-80 parts by weight of a lubricative acrylic urethane resin; 1-10 parts by weight of a colloidal composite oxide comprising zirconium, aluminum and phosphate-based compound; 1-10 parts by weight of a silane coupling agent; 1-18 parts by weight of silica; and 1-20 parts by weight of a water-soluble isocyanate crosslinking agent, based on 100 parts by weight of the total solid content of the composition.